Sudden death in cattle

What notifiable dx needs to be suspected if there is a sudden death?

Anthrax (Bacillus anthracis) —> suspected in carcass where animal died suddenly and no reasonable alternative diag or explanation

What are the features of anthrax?

• Bacteria form spores when exposed to air —> extremely resistant & can survive in soil for decades

• Usually peracute in ruminants —> no pre-mortem clin signs seen → animal found dead

What are the vet actions in terms of anthrax when farmer reports a sudden death?

If you have a sudden death and you can't rule out anthrax what should you advise the farmer?

The keeper must not:

• Move carcass (unless absolutely necessary)

• Cut skin of carcass

The keeper must:

• Prevent access to carcass / its discharges by people or animals

• Block drainage systems in vicinity of carcass

• Sterilise any milk from animal & any container/utensil that has contacted this milk.

What are some findings that indicate increased risk of anthrax?

• A hx of anthrax on premises

• Multiple sudden deaths w/ no explanation

• Recent disturbance of soil —> e.g. ditching, dredging, flooding

• Black tarry blood from nose / rectum

Give an overview of anthrax sampling

• Collect blood to make smears (w/o releasing blood into environ)

  • Usual site = ears —> available & relatively easy to contain any bleeding

• Make smears on farm and take swabs in case culture required

• Plug sampling site & body orifices w/ cotton wool soaked in approved disinfectant

• Don’t open carcase / use vacutainers or syringes —> as may aerosolise bacteria

How do you examine anthrax blood smears?

• Stained w/ Polychrome methylene blue (McFadyean’s stain)

• Large, square-ended rod w/ a pink capsule, usually forming chains

List the differentials for sudden death

• Anthrax

• Haemorrhage Calving injury, uterine prolapse (internal bleeding), milk vein, lung abscessation, abomasal ulceration

• Plant tox

• Lightning (insurance claim) —> PM exam

• Hypomagnesaemia —> time of year / weather

• Hypocalcaemia

• Bloat —> 1° / 2° / just PM

• Toxaemia (Mastitis, Metritis)

• Black leg (Clostridium chauvoei) —> skeletal / cardiac m.

• Black dx (Clostridium novyi) – liver

• Chemical poisoning – e.g. lead

• Electrocution

What plants can cause sudden death?

• Yew

  

• Acorns

Brought over by storms, hedge trimming

What is the pathogonmonic signs of lightning?

Singe marks

• Combine with environment assessment & weather data

What sample might you take for a hypomagnesaemia case post mortem?

Aqueous humour sample